Device for tensioning transport belts of different transport belt systems

ABSTRACT

A device for tensioning first and second transport belts in a folder of a rotary printing press including mutually independent transport belt systems wherein the first and second transport belts are disposed, includes a tensioning unit for tensioning the first and second transport belts. The tensioning unit is disposed between the first transport belt and the second transport belt and serves for acting thereon with a force that tensions the first and second transport belts simultaneously.

BACKGROUND OF THE INVENTION Field of the Invention

[0001] The invention relates to a device for tensioning transport belts of different transport belt systems, such as, for example, for transporing flat copies in folders disposed downstream from web-processing rotary printing presses.

[0002] German Published, Non-Prosecuted Patent Application DE 198 26 334 A1, corresponding to U.S. Pat. No. 6,073,755, has a tensioning device for a folder as its subject. According to the disclosure therein, a device is provided for tensioning transport belt systems for flat products in folders, which comprises a number of tensioning units. This number of tensioning units is associated with a corresponding number of transport belt systems, the transport belts of which revolve or circulate on endless paths. Each tensioning unit is fitted to a support so that it can rotate. Also provided are a number of rollers, of which each roller is connected to a corresponding tensioning unit so that the respective roller can rotate, and each of the rollers tensions a transport belt assigned to the respective tensioning unit. In the event of failure of one of the transport belts, the tensioning unit corresponding to that one of the transport belts which has failed and which is rotatably mounted on the support moves into a position that indicates failure of the transport belt. Using the tensioning units, each of which is assigned to the individual transport belts, respectively, of the transport belt system, the tension of each of the individual transport belts can be set and regulated independently for each of the transport belts.

[0003] U.K. Patent GB 2 299 327 B, corresponding to U.S. Pat. No. 5,688,219, discloses a transport system of a sheet folding machine. A large number of transport belts, respectively, form a frame around a number of deflection rings and a cylinder. Tensioning devices serve for maintaining tension in the belts. An individual tensioning element mounted on one side adapts to or fits the tension of a large number of belts. In order to make the removal and replacement of used transport belts easier, one end of each deflection ring and the appertaining end of the cylinder are detachable from the mounting thereof. Detachment can be carried out by axial division of the mounting from the corresponding ends of the deflection rings and the cylinder. For this purpose, the tensioning device is deactivated before the removal of the belt, in order to cause the individual transports belts to sag, which makes it easier to remove the belts. The deflection rings may assume the form of a coaxial disk. The cylinder to which the belts can be fitted can be, for example, a folding cylinder of a folder.

[0004] The construction disclosed by the aforementioned U.K. Patent GB 2 299 327 B, corresponding to U.S. Pat. No. 5,688,219, requires a relatively large amount of space in order to implement the necessary belt sag. The disadvantage of the construction disclosed by the aforementioned German Published, Non-Prosecuted Patent Application DE 198 26 334 A1, corresponding to U.S. Pat. No. 6,073,755, is that, as a result of the assignment of a tensioning unit to each transport belt, in the case of a hundred individual transport belts, difficulties with regard to accessibility may occur, and considerable costs may arise as a result of the use of up to a hundred individual tensioning units.

SUMMARY OF THE INVENTION

[0005] Taking into account the aforedescribed state of the prior art, it is an object of the invention of the instant application to provide a device for tensioning transport belts of different transport belt systems, which reduces the required number of tensioning units considerably per transport belt system in folders having a large number of individual transport belts.

[0006] With the foregoing and other objects in view, there is provided, in accordance with the invention, a device for tensioning a first and a second transport belt in a folder of a rotary printing press having mutually independent transport belt systems wherein the first transport belt and the second transport belt are disposed. A tensioning unit is provided for tensioning the first and second transport belts. The tensioning unit is disposed between the first transport belt and the second transport belt and serves for acting thereon with a force that tensions the first and second transport belts simultaneously.

[0007] In accordance with another feature of the invention, the tensioning unit comprises a first roller-like tensioning element serving for acting upon the first transport belt, and a second roller-like tensioning element serving for acting upon the second transport belt, the second roller-like tensioning element being movable with respect to the first roller-like tensioning element and being braced by a spring-elastic force.

[0008] In accordance with a further feature of the invention, the tensioning unit comprises an actuating cylinder to which a pressure medium is applicable for producing the force that tensions the first and the second transport belt.

[0009] In accordance with an added feature of the invention, the actuating cylinder is constructed as a double-acting actuating cylinder with two pressure chambers which can be acted upon separately from one another.

[0010] In accordance with an additional feature of the invention, the tensioning unit comprises a spring element serving for acting between the first tensioning element and the second tensioning element for producing the force that tensions the first and the second transport belts.

[0011] In accordance with yet another feature of the invention, the tensioning unit further comprises a system of spring elements connected in parallel, by which a stepped pretensioning force is producible.

[0012] In accordance with yet a further feature of the invention, the tensioning unit is disposed at least approximately horizontally oriented between the first transport belt and the second transport belt.

[0013] In accordance with yet an added feature of the invention, the tensioning unit is disposed at least approximately vertically oriented between the first transport belt and the second transport belt.

[0014] In accordance with yet an additional feature of the invention, the tensioning unit further comprises at least one guide element for preventing rotation of the tensioning unit.

[0015] In accordance with still another feature of the invention, at least one of the first tensioning element and the second tensioning element of the tensioning unit are mounted on extensible holding elements formed with a cross-sectional shape for preventing rotation of the first and the second tensioning elements from a vertical position thereof.

[0016] In accordance with still a further feature of the invention, the extensible holding elements have an hexagonal cross section.

[0017] In accordance with still an added feature of the invention, the holding elements are formed as multi-spline profiles.

[0018] In accordance with still an additional feature of the invention, the extensible holding elements are formed with a longitudinal groove, wherein a projection provided on a body of the tensioning unit is engageable.

[0019] In accordance with another feature of the invention, a multiplicity of tensioning units for tensioning a multiplicity of first and second transport belts are mounted so as to be positioned in a plane.

[0020] In accordance with a further feature of the invention, the plane is a horizontal plane.

[0021] In accordance with an added feature of the invention, the tensioning units are positioned parallel to one another on the holding element.

[0022] In accordance with an additional feature of the invention, the tensioning units are positionable on the holding element with an angular offset in relation to one another in the horizontal plane.

[0023] In accordance with yet another feature of the invention, the tensioning units are mounted in the holding element in a holder that is displaceable, within a guide region, relative to the holding element.

[0024] In accordance with a concomitant feature of the invention, the tensioning unit is disposed on a modified holding element and is enclosed by components of the modified holding element.

[0025] Advantages of the construction proposed by the invention result primarily from saving half of the tensioning units, when compared with the disclosed prior art construction, so that, first of all, a considerable cost advantage can be realized and, secondly, as a result of dispensing with a considerable number of tensioning units, the accessibility of the various copy transport systems in a folder is improved considerably. In addition, by using tensioning units which act in pairs on individual transport belts of different transport belt systems, a balancing or evening out of the belt tension and therefore improving the quality of the copy transport within a copy-processing machine, such as a folder arranged downstream of a rotary printing press, can be achieved.

[0026] In an alternate construction of the embodiment proposed in accordance with the invention, the tensioning units which are assigned, respectively, to pairs of individual transport belts of different transport belt systems can be disposed at least approximately oriented horizontally between these transport belt systems. In addition, it is likewise possible to arrange the tensioning units which are assigned, respectively, to pairs of individual transport belts of different transport belt systems in an at least approximately vertical orientation between these individual transport belts. If the tensioning units according to the two outlined fitting positions are arranged in a copy-processing machine, the accessibility to the tensioning units is particularly simple, and also simple and uncomplicated feeding of a pressure medium to tensioning units is possible if the tensioning units are constructed as actuating cylinders to which a pressure medium can be applied.

[0027] In addition to the construction of tensioning units assigned to the individual transport belts of different transport systems as actuating cylinders to which a pressure medium can be applied, the tensioning units can also include one or more spring elements. The spring elements can be enclosed by a covering; in addition to holding a spring element configured as a tension spring for acting upon the two roller-like tensioning elements provided on the tensioning unit, a spring system can also be provided, for example, springs connected in parallel or in series, via which the first roller-like tensioning element and the second roller-like tensioning element of the tensioning unit can be acted upon.

[0028] The tensioning units can be constructed as double-acting actuating cylinders with two pressure chambers which can be acted upon separately from one another, so that the respective individual transport belts of different transport belt systems for transporting flat copies can have impressed thereon either an identical pretensioning in both transport belts acted upon in pairs by the tensioning unit, or a different pretensioning.

[0029] In an alternative construction, the tensioning units can include guide elements, which extend at least approximately in the horizontal direction and on which the holding elements accommodating the roller-like first and second tensioning elements are guided. By having the guide elements act in the horizontal direction, rotation of the first and second tensioning elements fitted to extensible holding elements in relation to the individual transport belts of the various transport belt systems can be avoided, so that an at least approximately horizontal copy transport plane is established in the various transport belt systems, which promotes non-damaging and uniform copy transport. In order to prevent rotation of the roller-like first and second tensioning elements acted upon by the tensioning unit, the holding elements which can be extended from the interior of a single-acting or double-acting actuating cylinder can be formed with an hexagonal cross section, which prevents rotation of the holding elements of the first and of the second tensioning element in relation to the copy transport planes formed in the different transport belt systems. Instead of an hexagonal cross section which, respectively, accommodates the first tensioning element and the second tensioning element, the holding elements can also be formed from a multi-wedge profile; in addition, in one alternative embodiment of the holding elements, it is also possible to provide the latter with a longitudinal groove extending in the horizontal direction parallel to the extending and retracting movement of the first and second tensioning elements. A projection formed on the tensioning unit can engage in the longitudinal groove, so that the somewhat roller-like tensioning elements which accommodate the first and the second tensioning elements do not rotate relative to the copy transport plane in the mutually different transport belt systems.

[0030] In a further refinement of the idea upon which the invention is based, a number of tensioning units can be fixed to a holding element. The holding element can be configured as a beam-like element, which passes through a copy-processing machine, such as a folder, perpendicularly to the copy conveying plane. A number of tensioning devices can be fitted beside one another at intervals on the underside of this holding element, so that they are displaceable in a horizontal plane. The tensioning units, which act with a pretensioning force on pairs of individual transport belts of mutually different transport belt systems, can be fitted to the underside of the holding element both exactly parallel to one another and with an angular offset in relation to one another on the underside of the holding element. The angular offset of the tensioning unit in relation to a horizontally extending tensioning plane may be required to compensate for skewed positions or different extensions of individual transport belts and transport belt systems. The tensioning units, whether single-acting actuating cylinders, double-acting actuating cylinders or individual spring elements or spring systems, can be enclosed by a holder which, on the underside of the holding element, is accommodated in a guide whereon displacement of the holder and, therefore, of the tensioning unit accommodated therein, is possible. In this way, the tensioning units can be adjusted in the axial direction, i.e., in the direction of the copy transport path.

[0031] In a further variation in construction, the individual tensioning units which are assigned in pairs to individual transport belts and mutually different transport belt systems may be fitted to a modified holding element which encloses the tensioning units at the circumferential surface thereof.

[0032] The fixing or mounting of a number of tensioning units to a holding element which passes through a copy-processing machine perpendicularly to the copy of the transport plane, firstly, permits simple accessibility to the tensioning units and, secondly, simple feeding of a pressure medium to the tensioning units, if the latter are formed as single-acting or double-acting actuating cylinders. The device proposed by the invention may preferably be used on copy-processing machines, such as folders, which can be arranged downstream of a sheet-processing rotary press, whether it is a jobbing web-fed rotary press or a newspaper press.

[0033] Other features which are considered as characteristic for the invention are set forth in the appended claims.

[0034] Although the invention is illustrated and described herein as embodied in a device for tensioning transport belts of different transport belt systems, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

[0035] The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036]FIG. 1 is a diagrammatic side elevational view of an arrangement of transport belt systems, individual transport belts of different transport systems being assigned to a common tensioning unit;

[0037]FIG. 2 is an enlarged fragmentary view of FIG. 1, showing the tensioning unit with a compensation plane extending at least approximately horizontally;

[0038]FIG. 3 is a diagrammatic side elevational view of the tensioning unit thereof to a holding element;

[0039]FIG. 4 is a reduced bottom, side and end perspective view of FIG. 3, showing a number of tensioning units fixed horizontally adjacent one another to a holding element;

[0040]FIG. 5 is a reduced fragmentary bottom plan view of FIG. 4, showing a twin tensioning unit fixed to a holding element subdivided in horizontal direction;

[0041]FIG. 5.1 is a diagrammatic side elevational view of the twin tensioning unit fixed to the holding element;

[0042]FIG. 5.2 is a cross-sectional view of FIG. 5.1; and

[0043]FIG. 6 is another bottom, side and end perspective view of a plurality of tensioning units which are mounted on a holding element and, respectively, provided with a longitudinal guide.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] Referring now to the figures of the drawings and first, particularly, to FIG. 1 thereof, there is shown therein a configuration of transport belt systems. Individual transport belts of different transport belt systems of the configuration can be acted upon via a common tensioning unit.

[0045] Illustrated in an upper section of FIG. 1 are transport belt systems 1 and 2, within which a transport belt 3 and a further transport belt 4 are accommodated. The transport belt 3 and the further transport belt 4 run around deflection rollers 5 of a first diameter which are provided in each of the transport belt systems 1 and 2. Underneath the transport belt systems 1 and 2, a first transport belt system 6 and a further, second transport belt system 8 are illustrated. The first and the second transport belt systems 6 and 8, respectively, comprise a large number of individual transport belts arranged beside one another, of which, in the embodiment according to FIG. 1, a first individual transport belt is identified by reference character 6.1 and, in the second transport belt system 8, a second individual transport belt is identified by the reference character 8.1. Perpendicularly to the plane of the drawing of FIG. 1 and not illustrated therein, the first transport belt system 6 and the second transport belt system 8 comprise further individual transport belts which run at a short distance from one another around deflection rollers 7. By the arrangement of a plurality of individual transport belts perpendicularly to the plane of the drawing, a transport plane for flat copies is formed in the first transport belt system 6 and in the second transport belt system 8, respectively. Flat copies, for example, single-page or multi-page folded products, are conveyed in these transport planes in overlapped, i.e., imbricated, or in sequential order. In this way, the first transport belt system 6 cooperates with the transport belt system 1 arranged thereabove, the transport belt 3 and the individual transport belts of the first transport belt system 6 running through a common conveying section, wherein flat copies not illustrated here are gripped on the upper and lower sides thereof by the transport belts of the transport belt system 1 and of the first transport belt system 6, respectively. In an analogous manner, flat copies likewise gripped on the upper and lower sides thereof are conveyed between the transport belt system 2 and the second transport belt system 8 during the conveying section wherein the individual transport belts of these transport belt systems run parallel to one another.

[0046] The individual transport belts 6.1 and 8.1, respectively, singled out, by way of example, in FIG. 1, run around deflection elements 7, which are preferably formed as rollers. One of the deflection rollers 7, respectively, accommodated in the first transport belt system 6 and in the second transport belt system 8, respectively, is driven and impresses the conveying speed upon the individual transport belts of the first transport belt system 6 and of the second transport belt system 8, respectively, the conveying speed depending upon the conveying speed of the flat copies to be processed in a copy-processing machine.

[0047]FIG. 1 reveals that the first individual transport belt 6.1 of the first transport belt system 6, and the first individual transport belt 8.1 of the second transport belt system 8 are acted upon via a tensioning unit 9 which is common thereto. The tensioning unit 9 comprises an actuating cylinder 10, which can be acted upon via a connection, identified by reference numeral 13, for a pressure medium. In the actuating cylinder 10, there is displaceably accommodated a piston rod 11, at the end of which a second tensioning element 15 is fitted. The second tensioning element 15, constructed, in general, as a tensioning roller having webs surrounding the latter laterally and being rotatable on the piston rod 11, is located in a first position 15.1 in the view of FIG. 1. Furthermore, the tensioning unit 1 has a first tensioning element 14 which, in the view according to FIG. 1, is located in a first position 14.1. The first individual transport belt 6.1 of the first transport belt system 6 is acted upon via the first tensioning element 14 of the tensioning unit 9, while at the same time, by the second tensioning element 15 fitted to the extensible piston rod 11, the first individual transport belt 8.1 of the second transport belt system 8 is acted upon. The tensioning unit 9 thus acts simultaneously upon pairs of individual transport belts 6.1 and 8.1, respectively, of mutually different transport belt systems 6 and 8.

[0048] Instead of the first positions 14.1 and 15.1, respectively, of the first tensioning element 14 and of the second tensioning element 15, respectively, illustrated in FIG. 1, the tensioning elements 14 and 15, respectively, are also capable of assuming positions different from this position. A second position of the first roller-like tensioning element 14 is identified by reference character 14.2. In this position 14.2, a lower pretensioning is impressed upon the individual transport belt 6.1 of the first transport belt system 6 than in the position 14.1 of the first tensioning element 14 of the tensioning unit 9. The second tensioning element 15 rotatably mounted on the extensible piston rod 11 can assume a second position 15.2 and a further position 15.3 in addition to the position 15.1. Depending upon the extension travel of the piston rod 11 from the actuating cylinder 10 of the tensioning unit 9, a lower pretensioning is impressed upon the first individual transport belt 8.1 of the second transport belt system when the second tensioning element 15 is set in the position 15.2, as compared with the pretensioning which prevails in the first individual transport belt 8.1 of the second transport belt system 8 when the second tensioning element 15 assumes the position thereof identified by the reference character 15.3.

[0049] Depending upon the aging of the individual transport belts of the second transport belt system 8, an increase in the pretensioning can be produced in order to compensate for so-called transport-belt sag. Increasing the pretensioning of individual transport belts of transport belt systems is necessary, for example, when flat copies which comprise a plurality of folded layers are transported between the transport belts, for example, of the second transport belt system 8 and of the transport belt system 2. Due to the loading, the individual transport belts of the second transport belt system 8 tend to sag downwardly, so that contact between the upper side of the flat copies and the further transport belt 4 of the transport belt system 2 is no longer assured. Dog-eared corners and slipping of flat copies during their conveyance are consequences thereof. Therefore, a variation in the pretensioning of individual transport belts of transport belt systems is desirable.

[0050]FIG. 2 shows the tensioning unit illustrated in FIG. 1 with the assigned compensation plane.

[0051] In a manner analogous to that of the view according to FIG. 1, the tensioning unit 9 is mounted between two individual transport belts 6.1 and 8.1, respectively, of mutually different transport belt systems 6 and 8. The first tensioning element 14 provided on the tensioning unit 9 is located in the position 14.1, while the second tensioning element 15, which is mounted on the extensible piston rod 11, is shown in the first position 15.1 thereof. If the tensioning unit 9 is installed so as to be oriented in horizontal direction in a copy-processing machine, the result is a horizontal plane 20 wherein, depending upon the extent of travel of the piston rod 11 from the actuating cylinder 10 of the tensioning unit 9, further actuating positions, such as the second position 15.2, of the second tensioning element 15 may be set. As already mentioned in connection with the description of FIG. 1, different pretensioning force steps can be set in the first individual transport belt 8.1 of the second transport belt system 8. If a double-acting actuating cylinder 10 is used between the first individual transport belt 6.1 of the first transport belt system 6 and the first individual transport belt 8.1 of the second transport belt system 8, the first tensioning element 14 can also be fixed to a piston rod configured so as to be extensible from the interior of the actuating cylinder 10, so that the tensioning element 14 can likewise assume further actuating positions, such as the actuating position identified by the reference character 14.2. Both in the case of a single-acting actuating cylinder 10 and in the case of a double-acting actuating cylinder of a tensioning unit 9, in the event of a transport belt breakage, either in the first individual transport belt 6.1 of the first transport belt system 6 or in the first individual transport belt 8.1 of the second transport belt system 8, care can be taken that, due to the pairwise pretensioning of the two individual transport belts 6.1 and 8.1, respectively, via a common tensioning unit 9, the intact individual transport belt, i.e., the belt remaining serviceable, can be kept under pretensioning in the event of failure of the other transport belt. For this purpose, safety stops can be provided on the actuating cylinders 10, whether of single-acting or double-acting construction, to which a pressure medium can be applied at the connection 13.

[0052]FIG. 3 shows a tensioning unit carried by a holding element.

[0053] The accessibility of the tensioning unit 9 proposed in accordance with the invention in a copy-processing machine can be improved by providing a number of tensioning units 9 having a first tensioning element 14 acting upon a first individual transport belt and also a second tensioning element acting upon a further individual transport belt of a transport belt system that is different from the first transport belt system being fitted to a holding element 30. The holding element 30 can be configured as a beam-like element, which passes through the copy-processing machine, such as a folder, at right angles to the conveying direction of flat copies. The individual tensioning units 9 can be fitted displaceably to the underside of the holding element 30. Perpendicularly to the plane of the drawing in FIG. 3, a large number of tensioning units 9 can be fitted strictly parallel to one another on the underside of the holding element 30 or can be fitted with a slight angular offset in relation to one another. In order to permit an adjusting movement in the axial direction in relation to the tensioning unit 9, the respective tensioning units can be accommodated in a holder 33, which encloses a seat 34 corresponding to the holder on the actuating cylinder part 10 of the tensioning unit 9. The upper area of the holder 33 can be penetrated, for example, by a fixing element 32, with which the holder 33 is disposed on a guide underneath the holding element 30 so as to be displaceable relative to an opening 31. Depending upon the desired mounting position of the tensioning unit 9, the latter can be displaced on the holding element 30. As is additionally apparent from FIG. 3, the first and second tensioning elements 14 and 15, respectively, preferably configured as roller-like deflection rollers, are rotatable about rotational axes 49 and are not driven.

[0054] If the tensioning units 9 are constructed as single-acting or double-acting actuating cylinders 10 which can be acted upon via a pressure medium connection 13, the pressure medium is introduced into the cylinders via the connection 13. As an alternative thereto, it is likewise possible to configure the tensioning unit 9 as a spring tensioner, a spring element configured as a tension spring being incorporated between the first tensioning element 14 and the second tensioning element 15. Instead of a spring element acting upon the two tensioning elements 14 and 15, a spring system of springs connected in series or parallel can equally well be arranged in the tensioning unit 9, and with the springs, stepped production of a pretensioning force can be achieved in a tensioning unit 9.

[0055]FIG. 4 shows a number of tensioning units which are fixed to the underside of a holding element.

[0056] As shown in FIG. 4, the holding element 30 extends perpendicularly to the direction of movement of the second tensioning elements 15 of the tensioning units 9. The extent perpendicular to the direction of movement of the piston rods 11 is identified by reference numeral 35. The beam-like holding element 30 can be mounted by an upper side 37 thereof in a copy-processing machine, while the individual tensioning units 9 acting upon the individual transport belts of different transport belt systems in pairs are fixed, spaced apart axially from one another, to the underside 36 of the holding element 30. It is believed to be apparent from FIG. 4 that, in the embodiment illustrated therein, the individual tensioning units 9 are fitted to the underside 36 so as to be oriented strictly parallel to one another. The holders 33 of the actuating cylinders 10 of the tensioning units 9 are fixed to guide sections having slot-like openings 31 on the underside 36 of the holding element 30. The individual second roller-like tensioning elements 15 of the tensioning units 9 assume a first position 15.1, while the first tensioning elements 14 of the tensioning units 9 in the view according to FIG. 4 are illustrated in the first position 14.1 thereof. Both the roller-like second tensioning elements 15 and the roller-like first tensioning elements 14 rotate freely about the rotational axes 49 thereof at the ends of the tensioning units 9. Illustrated underneath the holders 33 for the actuating cylinders 10 of the tensioning units 9 are the connections 13 for a pressure medium. Fitting tensioning units 9 according to FIG. 4 to a common beam-like holding element 30 permits easy accessibility to the pressure medium connections 13 for the actuating cylinders 10 of the tensioning units 9. Instead of a strictly parallel arrangement of the individual tensioning elements 9 in relation to one another on the underside 36 of the beam-like holding element 30, if desired, the individual tensioning units 9 can also be mounted with a slight angular offset in relation to one another on the underside of the beam-like holding element 30. FIGS. 5, 5.1 and 5.2 reveal different views of a twin tensioning unit fixed to a horizontally divided holding structure.

[0057]FIG. 5 is a bottom plan view of a twin tensioning unit, i.e., two tensioning units 9 which are aligned parallel to one another and are arranged on lower parts 44 of a modified holding element 40. The tensioning units 9, respectively, comprise single-acting actuating cylinders 10, from which a piston rod is extensible. The actuating cylinders 10 are acted upon by a pressure medium, which is fed to the actuating cylinders via a connection 13 for a pressure medium. Fixed to the piston rods 11 of the tensioning units 9, respectively, are second holding pieces 39, to which the second, preferably roller-like tensioning elements 15 are fitted so that they can rotate freely about the rotational axes 49. At ends of the second tensioning elements 15, respectively, annular webs 48 are provided, which bound or limit a running or bearing surface 47 for the individual transport belts to be pretensioned.

[0058] Illustrated at the opposite end of the twin tensioning unit illustrated in FIG. 5 are first roller-like tensioning elements 14, which are mounted in first holding pieces 38. The first tensioning elements 14, illustrated in a first position thereof, likewise rotate about axes of rotation 49. The first tensioning elements 14, in a manner analogous to that of the second tensioning elements 15, are surrounded by webs 48 which extend annularly at the ends and bound or limit a running or bearing surface 47 for the individual transport belts to be pretensioned, which belong to the second transport belt system 8.

[0059] The tensioning units 9 according to FIG. 5 can be provided with single-acting actuating cylinders 10, at the end of which facing away from the connection 13 for the pressure medium, the first holding pieces 38 can be stationarily mounted. In another embodiment, the actuating cylinders 10 can also be constructed as double-acting actuating cylinders, wherein the first holding piece 38 can likewise be fitted to a piston rod that can be extended from the interior of the cylinder, so that the first holding piece 38 for the first tensioning elements 14 can likewise be moved relative to the body of the actuating cylinder 10.

[0060]FIG. 5.1 is a side view of the twin tensioning unit according to FIG. 5.

[0061] The side view according to FIG. 5.1 shows that the tensioning unit 9 is fitted to a modified holding element 40. The modified holding element 40 comprises an upper part 42, a center piece 43 and a lower part 44. The modified holding element 40 is mounted in a copy-processing machine by an upper side 37 of the holding element 40. Fixed to the underside 36 of the upper part 42 is the center piece 43, through which there extends a guide element 41 configured as a rod. The rod-like guide element 41 is fixed to a first holder 41.1 and to a second holder 41.2 on the actuating cylinder 10 of the tensioning unit 9. The rod-like guide element 41 penetrating the center piece 43 prevents the actuating cylinders 10 of the tensioning unit 9 from rotating relative to the modified holding element 40, which would otherwise result in a skewed position of the first tensioning element 14 and of the second tensioning element 15, which is most undesirable. The actuating cylinders 10 of the tensioning units 9 are connected by a lower part 44 to the center piece 43 of the modified holding element 40. The first tensioning element 14 is fastened stationarily by a first holding piece 38 to the end of the actuating cylinder 10 which is opposite the pressure medium connection 13, while the second tensioning element 15 is freely rotatably accommodated in a second holding piece 35 of the piston rod 11 of the actuating cylinder 10. From the sectional view of FIG. 5.2, which is taken along the line V.II shown in FIG. 5.1, it believed to be readily apparent that the center piece 43 is formed with slot-like openings 45, through which the rod-like guide element 41 extends, in order to prevent rotation of the tensioning units 9 in the installed position thereof in the center piece 43 and in the lower part 44 mounted on the underside of the center piece 43. The modified, preferably beam-like, holding element 40 is fixed in a copy-processing machine by the upper side 37 of the holding element 40, while the center piece 43 formed with the guide slots 45 is fitted to the underside 36 of the holding element 40. The sectional view of FIG. 5.2 further reveals that the piston rod 11 can be formed with an hexagonal profile 46, for example, as an antirotation safeguard. Instead of having an hexagonal profile 46, the piston rod 11 can also be formed as a multi-splined rod. Particularly simple in production terms and capable of production with little expenditure, a longitudinal groove can also be formed in the piston rod 11, for cooperating with a projection provided on the actuating cylinder 10, by which rotation relative to the horizontal plane 20 of the piston rod 11 and the second tensioning element 15 mounted thereon is avoided.

[0062]FIG. 6 is a perspective view of a plurality of tensioning units which are fitted to a holding element and, respectively, provided with a longitudinal guide for preventing a change in position in the circumferential direction.

[0063]FIG. 6 shows a number of tensioning units 9 mounted, in the center piece 43 and the lower part 44 cooperating therewith, at an underside 36 of a modified holding element 40. The center piece 43 formed with the slot-like opening 45 is penetrated by a rod-like guide element 41, which is mounted stationarily on each of the tensioning units 9 in a first holder 41.1 and a second holder 41.2. Holding the rod-like guide element 41 in a holding slot 45 in the center piece 43 prevents rotation of the actuating cylinders 10 relative to the center piece 43 of the modified holding element 40, so that the position of the first tensioning elements 14 and of the second tensioning elements 15, illustrated in FIG. 6, in relation to the copy-conveying plane defined by the individual transport belts to be tensioned is maintained in the various transport belt systems 6 and 8. The preferably roller-like first and second tensioning elements 14 and 15, respectively, comprise annular webs 48, which prevent the individual transport belts of mutually different transport belt systems from running off the running or bearing surface 47 formed between the webs 48. The roller-like first and second tensioning elements 14 and 15, respectively, which are located in the first position 14.1 and 15.1 thereof, respectively, in FIG. 6, are fitted to the ends of the tensioning units 9 so that they can rotate freely about the rotational axes 49. The piston rods 11, wherein the second tensioning elements 15 are fitted in FIG. 6, can be provided with an antirotation safeguard (note FIG. 5.2), so that the running or bearing surface 47 between the annular webs 48 at the ends of the second tensioning elements 15 always runs vertically.

[0064] Also shown in FIG. 6, a number of tensioning units 9 are fitted to the underside 36 of the modified holding element 40, the tensioning units 9 being spaced apart exactly parallel to one another. Instead of the exactly parallel alignment of a large number of tensioning units 9 in relation to one another, the center piece 43 and the lower part 44 cooperating with the latter can be displaced relative to one another parallel to the extent of width of the modified holding element 40, so that the tensioning units 9 can be displaced at an angle in the horizontal plane 20.

[0065] The device proposed according to the invention makes it possible to save half the actuating cylinders used for pretensioning individual transport belts in previous folder configurations. The arrangement of the individual tensioning units 9 on holding elements 30 and 40 firstly simplifies accessibility thereto, and secondly provides an optimum connection of feed lines 13 for a pressure medium acting upon the tensioning units 9, if actuating cylinders 10 which can be acted upon pneumatically are used. The use in folders which are arranged downstream of web-processing rotary printing presses and of a jobbing web-fed rotary press or a newspaper rotary press represents one possible field of use of the tensioning device proposed in accordance with the invention. 

We claim:
 1. In a folder of a rotary printing press having mutually independent transport belt systems with first and second transport belts, a device for tensioning the first and second transport belts, the device comprising: a tensioning unit for tensioning the first and second transport belts, said tensioning unit being disposed between the first transport belt and the second transport belt for acting thereon with a force tensioning the first and second transport belts simultaneously.
 2. The tensioning device according to claim 1, wherein said tensioning unit includes a first roller-like tensioning element for acting upon the first transport belt, and a second roller-like tensioning element for acting upon the second transport belt, said second roller-like tensioning element being movable with respect to said first roller-like tensioning element and being braced by a spring-elastic force.
 3. The tensioning device according to claim 1, wherein said tensioning unit includes an actuating cylinder for receiving a pressure medium for producing the force tensioning the first and second transport belts.
 4. The tensioning device according to claim 3, wherein said actuating cylinder is a double-acting actuating cylinder with two pressure chambers to be acted upon separately from one another.
 5. The tensioning device according to claim 1, wherein said tensioning unit includes a spring element for acting between said first tensioning element and said second tensioning element for producing the force tensioning the first and second transport belts.
 6. The tensioning device according to claim 5, wherein said tensioning unit includes a system of spring elements connected in parallel, for producing a stepped pretensioning force.
 7. The tensioning device according to claim 1, wherein said tensioning unit is oriented at least approximately horizontally between the first and second transport belts.
 8. The tensioning device according to claim 1, wherein said tensioning unit is oriented at least approximately vertically between the first and second transport belts.
 9. The tensioning device according to claim 1, wherein said tensioning unit includes at least one guide element for preventing rotation of said tensioning unit.
 10. The tensioning device according to claim 2, wherein at least one of said first tensioning element and said second tensioning element of said tensioning unit are mounted on extensible holding elements formed with a cross-sectional shape for preventing rotation of said first and said second tensioning elements from a vertical position thereof.
 11. The tensioning device according to claim 10, wherein said extensible holding elements have a hexagonal cross section.
 12. The tensioning device according to claim 10, wherein said extensible holding elements are formed as multi-spline profiles.
 13. The tensioning device according to claim 10, wherein said extensible holding elements are formed with a longitudinal groove, for engagement therein of a projection provided on a body of said tensioning unit.
 14. The tensioning device according to claim 10, wherein said tensioning unit is one of a multiplicity of tensioning units mounted to be positioned in a plane for tensioning a multiplicity of first and second transport belts.
 15. The tensioning device according to claim 14, wherein said plane is a horizontal plane.
 16. The tensioning device according to claim 14, wherein said tensioning units are positioned parallel to one another on said holding element.
 17. The tensioning device according to claim 16, wherein said plane is a horizontal plane, and said tensioning units are to be positioned on said holding element with an angular offset in relation to one another in said horizontal plane.
 18. The tensioning device according to claim 14, wherein said tensioning units are mounted in said holding element in a displaceable holder, within a guide region, relative to said holding element.
 19. The tensioning device according to claim 1, wherein said tensioning unit is disposed on a holding element and is enclosed by components of said holding element. 